Hydrogen sulfide (H2S) is a colorless gas with the characteristic foul odour of rotten eggs. It is a highly toxic, flammable and corrosive gas. Hydrogen sulfide has few important commercial uses. However, it is used to produce sulfur that is one of the most commercially important elements
It is not simply a byproduct of a chemical process but naturally occurs in coal pits, sulfur springs and gas wells. It can arise from the bacterial breakdown of organic matter in the absence of oxygen, commonly known as anaerobic digestion, therefore it is commonly encountered in places such as sewers, sewage treatment plants, manure stockpiles, mines, hot springs, and the holds of fishing ships. H2S also occurs in volcanic gases, natural gas, well waters and some hot springs emit some H2S. Industrial sources of hydrogen sulfide include petroleum and natural gas extraction and refining, pulp and paper manufacturing, rayon textile production, leather tanning, chemical manufacturing and waste disposal. Small amounts of hydrogen sulfide occur in crude petroleum.
Most countries have legal limits in force that govern the maximum levels of exposure to hydrogen sulfide in the working environment, typically around 10 ppm. The only reliable way to determine exposure levels is to measure the amount in the air. Regular monitoring will help to identify areas and operations likely to exceed exposure limits, and any areas that routinely pose a threat to over exposure should be equipped with continuous monitoring systems.
Portable gas detectors/alarms or direct reading gas detection instruments for the detection of dangerous levels of hydrogen sulphide, should be provided to people entering confined spaces that pose a risk such as manholes and pits. Single gas detectors or multi-gas monitors can be configured for the simultaneous detection of Hydrogen Sulphide alongside other potential atmospheric hazards including oxygen, combustible and toxic gases.
Applications include authorities, chemical, fire fighting, mining, oil and gas, pharmaceuticals and waste/water treatment plants that need to detect hazards such as a combustible atmosphere, oxygen deficiency or a toxic atmosphere.